The yeast propagation concept for breweries.

YEAST-STAR:

engineering for a better world GEA Process Engineering

2Always the right solution.

Our process systems focus on optimum process sequences,

hygienic design and gentle product handling. Whether you

choose a system featuring mainly standardized elements

or prefer to have it fully customized, you can be sure that

GEA Brewery Systems has the experience and the

understanding of customer requirements to offer you a

solution that is just right for you. When designing a new

system we utilize tried and tested principles, modifying them

as required to suit each individual case. This strategy ensures

optimized plant capacity and maximum functionality. For our

customers, this means system efficiency and reliability.

GEA Brewery Systems has gained a lot of experience

particularly in the field of yeast propagation. Together with

the state of the art and the requirements of our customers

this experience forms the basis of our yeast propagation

system YEAST-STAR.

Features of YEAST-STAR J Vigorous, actively fermenting yeast J Less equipment required J Optimal aeration rates J Circulation loop J Sterile air station with candle filter and product trap J Optional: In-line alcohol measurement, automatic

determination of yeast cell count, etc.

Vital in the fermenting cellar

yeast management

Yeast management is the core of a brewery. For ideal yeast

propagation and thus for a good beer hygienic plant

design is essential. Yeast quality is defined particularly

by the preservation of yeast viability and by optimized

yeast vitality. GEA Brewery Systems offers everything for

comprehensive yeast management.

Yeast is the most important component in beer production

its properties have a decisive influence on the quality,

flavour and filterability of the beer. As the variety of types

increases, the degree of automation often increases as well.

Thus, professional yeast management gains in importance.

Besides the selection of the right yeast strain, the cultivation

and propagation of healthy yeast cells, the recycling of

excessive yeast also plays an important role.

The aim is to create ideal conditions for the yeast from yeast

propagation through fermentation to the storage phase.

This is essential for a stable and reproducible fermentation

process and consistently high beer quality.

Yeast management systems from GEA Brewery Systems meet the highest hygienic standardsTanks and pipes are suited for hot cleaning the entire system can be steamed. Both aeration and homogeneous mixing take place with minimum shear stress.

3Standard solutions individually adjusted

Based on extensive experience in the field of yeast

propagation we have developed our standardized yeast

propagation system YEAST-STAR. The application and

combination of well-proven components and procedures

ensure very good yeast propagation characterized by high

reproducibility and remarkably high yeast quality.

The YEAST-STAR has four fundamental characteristics: J Gentle homogenization of the yeast suspension J Optimized aeration J Temperature control adapted to the overall process J Special yeast nutrition

The applied method is particularly gentle and adapts to the

specific requirements of yeast. With the special process

technology we optimize the propagation process and thus

speak of assimilation. The aim is to prepare the yeast for

the later fermentation conditions already during yeast

propagation.

Typical course of yeast propagationI: Lag phase (start-up phase)II: Log phase (logarithmic phase) assimilation processIII: Stationary phaseIV: Death phase

The degree of automation of the YEAST-STAR is adapted to customer requirements The capacity of the YEAST-STAR is designed according to the requirements of the brewery. Only in this way can the optimal yeast quantity be produced exactly when it is needed. With standardized calculation programs we can determine the design parameters of your YEAST-STAR quickly and easily, tailored to your individual needs.

The proven repeated-fed-batch process creates constantly

stable conditions in the propagation tank. Thus, the yeast does

not go through all physiological states: It stays permanently

in the logarithmic growth phase. This leads to actively

fermenting yeast with an especially high percentage of viable

cells. Furthermore, the requested yeast quantity is produced

within a short period of time. Depending on the nutrient

composition and the yeast strain, yeast cell counts of 100 to

120 million cells/ml are obtained with doubling times of

about 8 hours. Even cell counts of 160 million cells/ml have

been reached with the YEAST-STAR.

GEA Brewery Systems has developed three basic types of

yeast propagation systems which differ in the degree of

automation, from completely manual to fully automatic.

GEA Brewery Systems always has an appropriate solution.

The technical principles and the process control remain the

same.

Concentration [C]

Time [t]

I II III IV FeatureYEAST-STAR type

Basic Standard High-End

Overall system

Manual x

Semi-automatic x

Automatic x

Process connection Automatic x

Aeration Automatic x x

Homogenization Automatic x x

Temperature control Automatic x x

CIP connection Automatic x

4The main elements of the YEAST-STAR are two tanks

a propagator and an assimilator. Both tanks have the

same technical components, but they are used for different

processes.

The yeast quantity required for the assimilation process is

produced with the single-use method in the propagator. The

yeast suspension from a Carlsberg flask is filled into the

propagator and gradually mixed with fresh wort while it is

aerated and homogenized until the desired yeast quantity

with the requested cell concentration is obtained. Then the

propagator content is transferred into the assimilator, where

it is again gradually mixed with fresh wort, aerated and

homogenized. In this process, the required yeast quantity

for pitching in the fermentation tank as well as a residual

quantity that remains in the assimilator is produced. This

residue is used for the next propagation step in the repeated-

fed-batch process.

Homogenization

Advantages at a glance: J Particularly homogeneous mixing J Gentle to the product due to reduced shear forces and

little foam formation

The YEAST-STAR is based on the circulation of the

suspension through a circulation pipe by means of a speed-

controlled centrifugal pump.

Reduced flow rates of 1 m/s minimize the shear forces and

increase the vitality and viability of the yeast significantly.

The return socket of the circulation line is located

below the minimum filling level in the tank shell. The

special arrangement of the return socket ensures a very

homogeneous mixing of the tank content.

Focussing on the best possible yeast quality.

As there are no agitators, there is no risk of infection

caused by built-in components. Easy cleaning and the

corresponding microbiological safety are essential and are

special features of the YEAST-STAR.

Aeration

Advantages at a glance: J Additional mixing J Reduction of oxidative effects J Less foam formation J Excellent microbiological process safety

Aeration of the tanks is realized with a vertical aeration

pipe in the cone. The simple design without any rotating

internal components ensures optimal cleaning.

Moreover, a special product trap prevents the product from

flowing back into the sterile aeration system. Also here,

product safety is of paramount importance.

Aeration fitting in the tank outlet

Air

Tank outlet

5Whether aeration is done with oxygen or with air the

use of individually tailored measuring equipment ensures

optimal aeration control.

Everything is possible aeration over fixed time intervals

with specific volume flows, aeration that is adjusted to the

oxygen concentration or aeration dependent on the cell

count.

The measuring equipment and the degree of automation

of the YEAST-STAR are adapted to individual customer

needs. Excessive aeration is always avoided to reduce

oxidative effects and the discharge of yeast cells from the

suspension by foaming.

Temperature control

For a faster start of fermentation, conditions that are

similar to fermentation are created in the assimilator.

A temperature range of about 6 C above the fermentation

temperature has proven to be particularly suitable.

With this temperature range, the start of fermentation

is improved, which also has a positive effect on the

occupancy times of the fermentation tanks.

Nutrition

Advantages at a glance: J No sterilization of wort complete range of nutrients is

available J No overfeeding of yeast minimization of undesired

secondary processes

Not only in terms of temperature control, but also in terms

of nutrient supply the conditions should be similar to those

during fermentation.

Yeast that is actively fermenting right from the start

must be adapted to the nutrient composition. Therefore,

additional wort treatment steps like wort sterilization are

not performed in the basic system. Wort heating results in

a reduction of the worts nutrient content. Particularly the

complete spectrum of ingredients is necessary for yeast

propagation. If the yeast is not adapted to this range, there

may be negative effects even during fermentation.

Since the wort is not sterilized again, it is particularly

important that the propagation unit is manufactured

according to EHEDG guidelines. They are the basis

of our process systems. It is essential that the yeast

concentration does not fall below a minimum concentration

of approximately 20 million cells per ml, so that the

resistance of the yeast cells against infections is maximized.

Undesirable ancillary processes are minimized by the

improved ratio of yeast cell count to nutrient concentration.

Product trap for safe separation of sterile air from the process

6The following diagram shows the distribution of the ICP

value of a yeast sample measured in Weihenstephan.

The yeast quality was determined by flow cytometric

measurement of the intracellular pH value (ICP). The

distribution is almost completely above the value of 6.0 and

can thus be regarded as "very good".

Air supply and cleaning (CIP)

Advantages at a glance: J Microbiological safety due to excellent cleaning results J Flexible and compact design J Easy distribution and regulation of CIP/gas (supply and

removal)

Depending on the chosen degree of automation of the

system, the gas and CIP supply is also equipped with either

swivel bends or with automatic seat valves. With these

components it is possible to regulate the air supply and the

distribution of the cleaning medium.

The propagation tanks are supplied with the cleaning

medium through spray balls. The CIP medium is

accumulated in the tank and circulated through the

circulation pipe, so that all fittings are cleaned. The

connection for cleaning the aeration device is located in

the circulation pipe. So the aeration device can be cleaned

as well and there will be no unsprayed areas in the tank,

resulting in excellent cleaning.

Connection and yeast dosing

For correct dosing of the yeast, you have to know the yeast

quality and concentration. For this purpose, GEA Brewery

Systems provides various analysis tools, from volumetric

dosage up to viable cell count measurement.

Optimal yeast management plus suitable instrumentation

this ensures reproducible processes. And this has a

positive effect on the fermentation process, the filterability

and finally to the quality of the beer.

For such system concepts GEA Brewery Systems could

already develop numerous tailored solutions together

with customers and successfully integrate them in many

facilities all over the world.

Yeast quality Our conclusion.

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6 6.8 7.0

Cel

l co

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t

ICP

ICP distribution

Distribution of the ICP value in the yeast sample of a

German brewery

By means of the CIP return pump the cleaning medium is

removed from the yeast propagation system through the

CIP return line. It is also possible to sterilize all the piping

and tanks with steam.

7Step 1: Fill the content of the Carlsberg flask into the

propagator and gradually top up with wort.

Step 2: Transfer the propagator content into the

assimilator.

Step 3: Gradually fill the assimilator with wort until the

final volume is reached.

Advantages at a glance: J Maximum microbiological process safety because

the EHEDG guidelines are followed J High constant beer quality due to especially vigorous

and viable yeast cells J Essential nutrients are preserved as additional wort

treatment is avoided

J Little foam formation and homogeneous mixing thanks to gentle aeration and homogenization

J Highest possible flexibility due to direct adaptation to customer needs

J Optimized concept in terms of space requirements and costs

Step 4: 80 % of the volume are used for yeast dosing.

Step 5: Gradually top up the residue in the assimilator

with wort again until the target volume with the

requested cell count is reached.

YEAST-STAR optimized propagation with the two-tank method

FACTS & FIGURES:

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GEA Process Engineering

GEA Brewery Systems GmbH Huppmann Tuchenhagen

Locations:

Heinrich-Huppmann-Str. 1, 97318 Kitzingen, Germany Phone +49 9321 303-0, Fax +49 9321 303-603

Am Industriepark 210, 21514 Bchen, Germany Phone +49 4155 49-0, Fax +49 4155 49-2770

gea-brewerysystems @ gea.com, www.gea.com

We live our values.Excellence Passion Integrity Responsibility GEA-versity

GEA Group is a global engineering company with multi-billion euro sales and operations in more than 50 countries. Founded in 1881, the company is one of the largest providers of innovative equipment and process technology. GEA Group is listed in the STOXX Europe 600 index.